Work clamp



H. D. SNELL June 17, 1952 WORK CLAMP Filed April 10, 1947 2 SI-IEETS-SHEET l Hbrm' Duncan Snell H. D. SNELL June 17, 1952 WORK CLAMP Filed April 10, 1947 2 SPEETS-SHEET 2 Inventor Harm Duncan Snell Patented June 17, 1952 WORK CLAMP -Harm 'Duncan Snell, Port Arthur, Tex., assignor of twenty-five per cent to Jo Ann Snell, Port Arthur, Tex.

Application April 10, 1947, Serial No. 740,697

4 Claims.

My invention relates to improvements in work clamps for holding work, especially, while drilling through the same.

The primary object of my invention is to provide a simply constructed, easily operated :clam for securely holding work upon opposite sides of a drill, or other tool, being used to form a hole through the work, and which is adjustable to properly clamp work of different thicknesses and adapted for locking in clamping position.

Another object is to provide a clamp of the type and for the purpose above set forth which is safe to use, will not quickly get out of order, and is comparatively inexpensive to manufacture.

To the accomplishment .of the above, and subordinate objects presently appearing, the preferred embodiment of my invention has been illus'tra'ted in the accompanying drawings, set forth in detail in the .succeeding description, and defined in the claims appended hereto.

'In said drawings:

Figure 1 is a view in side elevation of my improved clamp in the preferred embodiment thereof, the clamp being shown as closed;

Figure .2 is a view in plan;

Figure .3 is a view in longitudinalsection taken on1the:line .3i3 of Figure 2;

Figure "4 is a view in'transverse section taken on the line 4-4 of Figure 1;

Figure is a .view in plan-of the front tubular section of the :hand lever;

Figure -'6:is a viewin :plan of the yoke.

Referring 'to the drawings by numerals, my improved clamp, as illustrated, comprises, .as its basic element, :an elongated, rectangular plate I provided with a rear end handle 2 coplanar therewith, and having a frontend clamping section 3 'with a top work-clamping face 4 serrated to prevent the work from slipping thereon. A transverse Vegroove 5 is provided in the top side of .said section 3, anda clearance hole in said section in the transverse center of saidgroove 5, for a purpose presently seen.

A (pair of side bearing plates "I, of any suitable form, are secured to opposite side edges of the plate I immediately in the rear of the front end clamping section 3, byscrews :8.

A screw shaft ll is journa'led at itsends in said bearing plates "I to extend transversely over the top of the plate I and which is provided with a central, knurled collar ID for manually rotating the same, and with right and left hand screw thread sections I I, I2 upon opposite sides of said collar.

A pair of curvilinear clamping fingers I3 are threaded, at rear ends thereof, onto said sections II, 1.2 of the screw shaft, upon opposite sides of the collar I I3, and which arch away from the work-clamping face 4 of the front end clamping section 3 and are adapted to be swung, on said screw shaft 9 into and from clamping relation to said work-clamping face 4. As will be clear, the clamping fingers I3 are arranged upon opposite sides of the longitudinal center of the plate I and when said fingers are in clamping engagement, serrated clamping ends I4 thereof overlie the V-groove 5 upon opposite sides of theclearance hole 6. The purpose of this will presently appear. By rotating the screw shaft 9 in opposite directions, respectively, the clamping fingers I3 may be variably spaced apart to correspondingly space the clamping ends M thereof different distances from the clearance hole '6, the purpose of which will also presently be seen. 7

For swinging the clamping fingers I3, the following means is provided. On the top side of the plate'I, and adapted to extend along the handle 2, is a hand lever I5 mounted, as presently described, to be swung toward and from said plate and handle, and comprising a front tubular section I6 and a rear tubular section I1 with a rear end closure plug I8 threaded therein, said rear section I -'I being threaded onto said front section I6 for adjustment thereon. The fronttubular section I6 is formed with a forked front end I 9 which is pivoted by studs '20 between a pair of laterally spaced ears ZI on top of the plate I and so that said hand lever I5 is swingable toward and from said plate I and handle 2 about an axis parallel to the axis of the screw shaft '9 and in the rear of said shaft.

A rod 22 is slidably extended through the front tubular section I6 of the hand lever I5 with a radial front end ear 23 thereon extending laterally out of said section adjacent to the forked end I9. A nut 24 on the rear end of said rod 22 is adapted to engage an internal, annular shoulder 25 in the rear tubular section I! and thereby limit forward sliding of said rod 22 in said section I6. A washer 26 on said rod 22, and a screw 21 in the rear end of said rod, lock the nut 24 against turning. A coil spring 28 interposed in the rear tubular section ll of the hand lever I5, between the screw plug I8 and said washer 26, tensions said rod 22 against rearward sliding in said section I6 and tends to maintain said rod in its forward limit of sliding movement. The front and rear sections I6, I7, the plug I8, and nut 24 and coil spring 28 form 3 screw feed means for adjusting the rod 22 endwise in the hand lever I for a purpose presently seen.

A T-shaped yoke 29 has a bifurcated rear end 30 straddling the car 23 and pivoted thereto by a pin 3| parallel with the axis of the pivot studs 20 and the axis of the screw shaft 9. At its other end, the yoke 29 is provided with laterally spaced ears 32 alternating with right-angled crank arms 34 on the clamping fingers [3. A pivot rod 35 extends through said cars 32 and arms 35 and on which the crank arms 35 are laterally slidable to permit the described variable spacing thereof. 7

A stop bolt 36 in the plate I coacts with the front tubular section It of the hand lever l5 to limit swinging movement of said lever toward the plate l and handle 2. In this limit of movement of the hand lever 15, the axis of the pivot pin 3| and that of the pivot rod 35 are located intermediate the plate I and the axis of the pivot studs 20 comprising the pivotal axis of the hand lever l5, so that the described means for swinging the clamping fingers I3 is in a past dead center position.

Referring now to the operation of the described clamp. To open said clamp, the hand lever I5 is swung away from the plate I and handle 2, as shown in dotted lines in Figure 3. During such swinging of said lever l5, the rod 22 exerts end thrust against the yoke 29 which thereby, through the crank arms 34, swings the clamping fingers l3 counter clockwise, as viewed in Figures 1 and 3, from clamping relation to the work-clamping face 4 of the front end clamping section 3 of the plate I. A piece of work, for instance, a strip, not shown, of a given gauge, is then placed on the work-clamping face 4 of said section 3 to extend along the V-groove 5. With one hand grasping the handle 2, the hand lever I5 is then swung toward the plate l and said handle 2 into its described limit of swinging movement in that direction. During such swinging of said hand lever I5, the rod 22 exerts a pull on the yoke 29 which, through the crank arms 34, swings the clamping fingers l3 clockwise to clampingly engage the clamping ends I 4 thereof with the strip and clamp the same to said clamping face 4. As has already been described, in this limit of swinging movement of the hand lever l5, the clamping finger swinging means, of which said lever forms a part, is in past dead center position. Thus the clamp is positioned to be locked closed. By turning the rear tubular section I! of the hand lever IS on the front tubular section [6, the rod 22 may be adjusted endwise inwardly of the hand lever 15 to tighten the clamping fingers I3 against the work and lock the described clamping finger swinging means in past deadcenter position and the clamp closed. Also, said section I! may be turned to adjust the clamping ends H! of the clamping fingers l3 relative to the hand lever l5 to variably space said ends I from the clamping face 4 so that when the hand lever I5 is swung toward the plate I and the handle 2 into its limit of movement in that direction, said ends (4 will clampingly engage work of different thicknesses with the desired pressure. To open the clamp, the tubular section I! is turned on said section it to adjust the rod 22 endwise outwardly of the hand lever 15 to release the clamping fingers l3 so as to break the past dead-center lock. The spring 28, as will be seen, provides for yielding endwise movement of the rod 22 outwardly relative to the hand lever I5 so that said lever may be swung in opening the clamp. After the work or strip is clamped as described, it may be drilled with any suitable tool in the line of the clearance hole 6. The V-groove 5 provides an aligning guide for the work, or strip, as will be understood.

The foregoing will, it is believed, suffice to impart a clear understanding of my invention without further explanation.

Manifestly, the invention, as described, is susceptible of modification without departing from the inventive concept, and right is herein reserved tosuch modifications as fall within the scope of the appended claims.

What I claim is:

1. In a work clamp, a work supporting plate, a pair of laterally spaced bearing members extending from said plate at a right angle thereto, a manually rotatable shaft extending across said plate with ends journalled in said members, said shaft having right and left hand screw thread sections on opposite sides of its transverse center, a pair of curvilinear clamping fingers threaded on said sections for relative adjustment laterally by rotation of said shaft and for swinging about said shaft to clampingly engage corresponding ends thereof with the work at difierent points thereon, a handle pivotally mounted on said plate for swingin about a fixed axis, and a connection between said handle and both said fingers for swinging said fingers into work engaging position by swinging of said handle.

2. In a work clamp, a work supporting plate, a shaft extending across said plate with ends mounted thereon, a pair of clamping fingers swingably mounted at corresponding ends thereof on said shaft in laterally spaced relation for engaging the work atdiiferent points thereon and being swingable into work engaging position, an elongated tubular handle pivotally mounted at one end on said plate for swinging movement, a connecting member pivoted to said handle and both said fingers for swinging said fingers into work engaging position upon swinging of said handle, the pivots of said connecting member assuming past dead center position relative to the pivot of said handle when said fingers are in work engaging position, and screw feed means embodied in said handle for locking said pivots in past dead center position.

3. In a work clamp, a work supporting plate, a shaft extending across said plate with ends mounted thereon a pair of clamping fingers swingably mounted at corresponding ends thereof on said shaft in laterally spaced relation for engaging the work at different points thereon and being swingable into work engaging position, an elongated tubular handle pivotally mounted at one end on said plate for swinging movement, a yoke pivotally connected at one end to said fingers, a rod in said handle with the other end of said yoke pivoted thereto, said rod being swingable by said handle to cause said yoke to swing said fingers into work engaging position with the pivots of said yoke in past dead center relation to the pivot of the handle, said rod being slidable in said handle to lock said pivots in past dead center position, and screw feed means embodied in said handle for sliding said rod.

4. In a work clamp, a work supporting plate, a clamping finger, means pivotally mounting 5 r said finger to said plate for swinging toward the plate to clampingly engage work supported on the plate, and means for swinging said finger comprising a handle including a tubular section pivotally mounted at one end to said plate for swinging toward said plate, a rod endwise slidable in said section with a lateral ear on one end thereof, a yoke pivoted at one end to said finger and pivoted at its other end to said ear, the pivots of said yoke assuming past dead center relation to the pivot of said section when said section is swung toward said plate and said fingers are clampingly engaged with the work, a second tubular handle section threaded onto the first named section for screw feed movement thereon and into which the other end of said rod extends and is provided with a nut thereon, and a shoulder in said second section movable against said nut upon screw feed of said second section to thereby slide said rod and lock said yoke against movement of its pivots out of past dead center relation to the pivot of said first named section.

HARM DUNCAN SNELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

